Fabrication of interdigitated electrode (IDE) based ZnO sensors for room temperature ammonia detection

Interdigitated electrode (IDE) sensor has been successfully fabricated, characterised and successfully used for ammonia sensing. Silver (Ag) is used as IDE which is fabricated by using DC magnetron sputtering while ZnO sensing layer with three different dopants (Cd, Mg and Y) have been deposited over the Ag sputtered IDE by RF magnetron sputtering. The deposited sensing layer has been characterised by X-ray diffraction (XRD), Photoluminescence (PL) and Hall effect which reveal that typical ZnO characteristics. The room temperature current-voltage characteristics of the fabricated device show the ohmic behaviour for sensors SD1 (10 mol% Cd doped ZnO) and SD2 (10 mol% Mg doped ZnO) while Schottky behaviour for the sensor SD3 (2 mol% Y doped ZnO). The fabricated IDE sensors were exposed to the various concentration of ammonia, and the enhanced ammonia response has been observed compared to thin film sensors. The sensors SD1 and SD2 show higher ammonia response than SD3. However, fast response and speed recovery time were realised for device SD3 compared to SD1 and SD2. Among the three sensors, SD1 shows the maximum ammonia response. The enhanced ammonia sensing of fabricated sensors explained by band bending mechanism in detail. (C) 2020 Elsevier B.V. All rights reserved.